some employers not accepting temporary SSN

[amartins 11]

She should return to the store and get the job/contact information for the regional manager, because, H&M does not want its uninformed employees breaking the law, which this manager has ostensibly done.

Some people have touched on this, but, simply, she never has to physically present her social security card. She has to provide the number. From the Department of Justice (underlining mine):

Q. My employer asked me to verify my employment eligibility by showing a document issued by the Department of Homeland Security because I am not a U.S. citizen. Is that permissible?

A. No. For employment eligibility verification, a worker must be allowed to choose which documents to show from the Form I-9 Lists of Acceptable Documents. If the documentation reasonably appears to be genuine and to relate to the worker, the employer must accept it. An employer may be violating the anti-discrimination provision of the INA if the employer requires a worker to show specific documents or more documents than required based on the worker's citizenship status or national origin. If your employer has demanded a specific document from you for I-9 purposes, contact OSC.

Further, from the SSA (bold mine):

Employers often ask to see an employee’s Social Security card. The Internal Revenue Service’s Publication 15 (Circular E), Employer’s Tax Guide, states, “You should ask your employee to show you his or her social security card. The employee may show the card if it is available.” But, do you really need to see the card? While not required, SSA provides a service for employers to verify a name and SSN for wage reporting purposes when you want additional assurance of an employee’s correct name and SSN.

Since 1936, Social Security has issued over 30 different versions of the Social Security number (SSN) card which makes it difficult to recognize a valid card. Sometimes when you ask an employee to show you their card the card is not available. In either case, you don’t have to send them to a local Social Security office. Consider using the free Social Security Number Verification Service (SSNVS) which allows registered employers to quickly verify whether a person’s name and SSN match Social Security’s records. It saves you and the employee time.

Edit: the I-9 lists the EAD in List A, so that's all that she has to show.

Edited March 26, 2015 by amartins